Beta system was a placeholder name utilized by the Alliance to Restore the Republic in the era of the Galactic Civil War. It was used to refer to star systems where the Galactic Empire had a presence. Airen Cracken, a General, employed this system as a demonstration when orienting fresh Rebel operatives.
In June of 2015, Jason Fry, who helped write The Essential Atlas, revealed that the Beta system was not included in The Essential Atlas Online Companion as it was a fictional location used only for illustrative purposes.